In this photo provided by the Russian Emergency Situations Ministry, emergency personnel collect wreckage of an AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Human error may be to blame for the crash of a Russian plane that killed 71 people, Russian investigators said Tuesday, noting that the plane's pilots failed to turn on the heating unit for its measuring equipment, resulting in flawed speed data. (Russian Ministry for Emergency Situations photo via AP)

In this photo provided by the Russian Emergency Situations Ministry, the wreckage of an AN-148 plane crash collected by emergency personnel are seen in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Human error may be to blame for the crash of a Russian plane that killed 71 people, Russian investigators said Tuesday, noting that the plane's pilots failed to turn on the heating unit for its measuring equipment, resulting in flawed speed data.(Russian Ministry for Emergency Situations photo via AP)

In this photo provided by the Russian Emergency Situations Ministry, emergency personnel collect wreckage of an AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Human error may be to blame for the crash of a Russian plane that killed 71 people, Russian investigators said Tuesday, noting that the plane's pilots failed to turn on the heating unit for its measuring equipment, resulting in flawed speed data. (Russian Ministry for Emergency Situations photo via AP)

In this photo provided by the Russian Emergency Situations Ministry, emergency personnel collect wreckage of an AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Human error may be to blame for the crash of a Russian plane that killed 71 people, Russian investigators said Tuesday, noting that the plane's pilots failed to turn on the heating unit for its measuring equipment, resulting in flawed speed data. (Russian Ministry for Emergency Situations photo via AP)

In this photo provided by the Russian Emergency Situations Ministry, emergency personnel prepare to pull out debris of an engine of the AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Emergency teams combed the snowy fields outside Moscow on Monday, searching for debris from a crashed Russian airliner and the remains of the 71 people aboard it who died. (Russian Ministry for Emergency Situations photo via AP)

In this photo provided by the Russian Emergency Situations Ministry, emergency personnel load debris of an engine of the AN-148 plane crash on a truck in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Emergency teams combed the snowy fields outside Moscow on Monday, searching for debris from a crashed Russian airliner and the remains of the 71 people aboard it who died. (Russian Ministry for Emergency Situations photo via AP)

In this handout photo released by the Moscow-based Interstate Aviation Committee on Monday, Feb. 12, 2018, the flight recorders of a Russian passenger plane that crashed near Moscow, killing all 71 people on board are displayed at the Moscow-based Interstate Aviation Committee in Moscow, Russia. The An-148 regional jet operated by Saratov Airlines plummeted into a field minutes after taking off Sunday from Moscow's Domodedovo Airport and exploded in a giant fireball. (Interstate Aviation Committee via AP)

In this photo provided by the Russian Emergency Situations Ministry, an emergency team works at the scene of a AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Investigators are studying the information from flight recorders of a Russian passenger plane that has crashed near Moscow killing all 71 people on board. The Moscow-based Interstate Aviation Committee said Tuesday its experts managed to recover the data from both the plane’s flight data and cockpit conversation recorders. (Russian Ministry for Emergency Situations photo via AP)

Personnel work at the scene of the AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Moday, Feb. 12, 2018. The Russian passenger plane carrying 71 people crashed Sunday near Moscow, killing everyone aboard shortly after the jet took off from one of the city's airports. The Saratov Airlines regional jet disappeared from radar screens a few minutes after departing from Domodedovo Airport en route to Orsk, a city some 1,500 kilometers (1,000 miles) southeast of Moscow. (AP Photo/Alexander Zemlianichenko)

In this photo provided by the Russian Emergency Situations Ministry, emergency personnel works at the wreckage of an AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Emergency teams combed the snowy fields outside Moscow on Monday, searching for debris from a crashed Russian airliner and the remains of the 71 people aboard it who died. (Russian Ministry for Emergency Situations photo via AP)

Orthodox youth with a priest gather at the Cathedral of Christ the Savior in Moscow lighting 71 candles in memory of those killed in the An-148 plane crash, Monday, Feb. 12, 2018. A Russian passenger plane carrying 71 people crashed Sunday near Moscow, killing everyone aboard shortly after the jet took off from one of the city's airports. The Saratov Airlines regional jet disappeared from radar screens a few minutes after departing from Domodedovo Airport en route to Orsk, a city some 1,500 kilometers (1,000 miles) southeast of Moscow. (AP Photo/Alexander Zemlianichenko)

A girl places a candle as a group gather at the Cathedral of Christ the Savior in Moscow to light 71 candles in memory of those killed in the An-148 plane crash, on Monday, Feb. 12, 2018. A Russian passenger plane carrying 71 people crashed Sunday near Moscow, killing everyone aboard shortly after the jet took off from one of the city's airports. The Saratov Airlines regional jet disappeared from radar screens a few minutes after departing from Domodedovo Airport en route to Orsk, a city some 1,500 kilometers (1,000 miles) southeast of Moscow. (AP Photo/Alexander Zemlianichenko)

Emergency workers explore the site of a AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Monday, Feb. 12, 2018. Emergency teams combed the snowy fields outside Moscow on Monday, searching for debris from a crashed Russian airliner and the remains of the 71 people aboard it who died. The An-148 twin-engine regional jet bound for Orsk in the southern Urals went down minutes after taking off from Moscow's Domodedovo airport Sunday afternoon. All 65 passengers and 6 crew on board were killed. (AP Photo/Nikolay Koreshkov)

In this photo provided by the Russian Emergency Situations Ministry, emergency personnel works at the scene of an AN-148 plane crash in Stepanovskoye village, about 40 kilometers (25 miles) from the Domodedovo airport, Russia, Tuesday, Feb. 13, 2018. Emergency teams combed the snowy fields outside Moscow on Monday, searching for debris from a crashed Russian airliner and the remains of the 71 people aboard it who died. (Russian Ministry for Emergency Situations photo via AP)

MOSCOW (AP) — Human error may be to blame for the Russian plane crash that killed 71 people, Russian investigators said Tuesday, noting that the plane's pilots failed to turn on the heating unit for its measuring equipment, resulting in flawed speed data.

After studying the An-148's flight data recorder, the Interstate Aviation Committee said that Sunday's crash near Moscow occurred after the pilots saw conflicting data on the plane's two air speed indicators.

The flawed readings came because the pilots failed to turn on the heating unit for the plane's pressure measurement equipment prior to takeoff, the committee said.

The pilots had placed the An-148 on autopilot after taking off from Moscow's Domodedovo Airport but took its manual controls back when they heard alarm signals warning of conflicting speed data. One indicator showed the plane's speed at zero, investigators said.

The pilots then performed a series of maneuvers and eventually took the plane into a dive at 30-35 degrees. It plummeted into a snowy field outside of Moscow six minutes after takeoff, killing all 65 passengers and six crew onboard.

The committee said it is continuing to study the data, but noted that "erroneous data on the pilots' speed indicators may have been a factor that triggered the special flight situation."

It emphasized that the flawed speed data resulted from the "icing of pressure measurement instruments that had their heating systems turned off."

The RBC news outlet quoted pilot Andrei Litvinov as saying the pilots probably took the plane into a dive because of low speed readings to avoid stalling and didn't have time to correct their mistake at such a low altitude.

Earlier reports indicated the plane's captain had chosen not to have the plane undergo de-icing before takeoff. The crew decides whether to have the plane sprayed by de-icing liquid, depending on weather conditions and the state of the plane.

Saratov Airlines, which operated the plane, said its captain had more than 5,000 hours of flying time, 2,800 of them in an An-148, and the other pilot had 812 hours of experience, largely in that model.

The aviation committee's description of the Moscow crash resembled the 2009 crash of an Air France Airbus 330 over the Atlantic Ocean, which killed all 228 people aboard. Ice crystals blocked pressure sensors responsible for air speed indication, and erroneous speed readings misled the pilot, who pitched the Air France plane sharply up instead of down as it stalled and lost control.

A crash of another An-148 in March 2011 during a training flight in Russia that killed all six crew members on board was also linked to a faulty pressure instrument resulting in wrong speed readings, prompting the confused crew to exceed the permissible speed limit.

The An-148 model itself has a very spotty safety record, with two crashes and a string of major incidents in which pilots struggled to land safely. Saratov Airlines has grounded other An-148s in its fleet pending the Moscow crash investigation.